Calculating Boost using MAP
Thread Starter
Pro
Joined: Nov 2007
Posts: 605
Likes: 15
From: Rocky Mountains Colorado
Calculating Boost using MAP
I have been using HP Tuners and the custom PID for boost to provide me with boost readings for my E-Force. However, after installing Beta version 2.23.410 of HP Tuners, my boost readings went goofy because of a bug in the Beta version of HP Tuners (Bill has added this bug to his list of Beta issues). To obtain my boost readings in the absence of a boost gauge and HP Tuners PID, I have been using the following calculation using the output readings of the MAP.
Example: Data Log of my last run at Bandimere on 10/05/2011
MAP reads 142 kPa @ 6,300 rpm
Converting kPa to psi multiply 142 kPa by .1450377377 = 20.5905358
The DA or effective altitude of this data logged run was 8,400'
The atmospheric pressure at 8,400' is 10.75 psi
20.59 psi @ 6,300 rpm less 10.75 psi @ 8,400' = 9.84 lbs of boost.
This is how I determine boost developed by my E-Force. In the absence of a boost gauge, is this an accurate representation of the boost developed by my E-Force?
Example: Data Log of my last run at Bandimere on 10/05/2011
MAP reads 142 kPa @ 6,300 rpm
Converting kPa to psi multiply 142 kPa by .1450377377 = 20.5905358
The DA or effective altitude of this data logged run was 8,400'
The atmospheric pressure at 8,400' is 10.75 psi
20.59 psi @ 6,300 rpm less 10.75 psi @ 8,400' = 9.84 lbs of boost.
This is how I determine boost developed by my E-Force. In the absence of a boost gauge, is this an accurate representation of the boost developed by my E-Force?
Safety Car
Joined: Jun 2004
Posts: 4,353
Likes: 22
From: Bella Vista Ca
I have been messing around with mine lately making a custom PID. I have a boost gauge but All 4 of the inputs are used leaving me with out one for the boost gauge.
I'm running a 3 bar on a 04 PCM, this might give you some ideas. The numbers I get with this are very close. PID 2334 Baro sensor and PID 2340 3 bar sensor.
Sensor: None
Units: LBS
Function:
([PID.2334]-[PID.2340])/6.8947572803
I'm running a 3 bar on a 04 PCM, this might give you some ideas. The numbers I get with this are very close. PID 2334 Baro sensor and PID 2340 3 bar sensor.
Sensor: None
Units: LBS
Function:
([PID.2334]-[PID.2340])/6.8947572803
Team Owner
Joined: Nov 2007
Posts: 24,035
Likes: 2,342
From: Gilbert AZ
Safety Car
Joined: May 2006
Posts: 4,016
Likes: 93
From: St. Louis, MO
Tech Contributor
The baro value doesn't reset in boost if you run a custom OS, as HP Tuners has baro updating disabled in those systems.
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Pro
Joined: Mar 2006
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From: calgary alberta
Thread Starter
Pro
Joined: Nov 2007
Posts: 605
Likes: 15
From: Rocky Mountains Colorado
Thanks to everyone for their input. I use the MAP output of HP Tuners as read in kPa. I convert the MAP reading from kPa to psi. The altitude at Bandimere is 5,800' but the more accurate representation of altitude is the DA or effective altitude which is listed for each pass through the 1/4 mile. I use DA which I believe gets me real close to actual boost realized. I've given up on the custom PID for boost as my Beta Version of HP Tuners has a bug in it and my boost readings are through the roof (example 144 kPa reads boost of >120 lbs of boost). William/Bill of HP Tuners is looking into a fix for the bug in the Beta Version.
